It’s true that Senator Marco Rubio’s stated principles for comprehensive immigration reform are quite similar to President Obama’s. It’s also true that when Rubio attacks the president over reform, as he did after a White House legislative draft leaked last weekend, he’s signaling to his fervently anti-Obama base that he’s still a solid Tea Party Republican. As I wrote in my Rubio profile, “some of this is Beltway theater; reform could become toxic to Republicans if it’s perceived as Obama-friendly.” This is why smart restrictionists like Mark Krikorian of the National Review as well as smart reformers like Benjy Sarlin of Talking Points Memo seem to agree that Rubio is just posturing, that what really matters are the similarities between his principles and the president’s, that the partisan theater is designed to reduce Republican resistance to bipartisan reform.

Well, maybe. Obama did call Rubio in Jerusalem Tuesday night, and both sides expressed ritual optimism. But there are some real differences between Rubio and Obama on immigration. Sure, Rubio’s rhetoric could help make reform politically palatable to Republicans, and even help move reform substantively to the right. But it could also help lay the groundwork for Rubio to scuttle reform, accuse Obama of overreaching, and claim credit for trying to forge a bipartisan solution. Beltway theater can have real consequences, and the more Rubio threatens to walk away from any deal that doesn’t include everything he wants, the more pressure he will face to walk away when the deal, inevitably, doesn’t include everything he wants. Nobody but Rubio knows how far he is willing to bend to cut a deal few of his supporters want with a president most of his supporters despise.

Remember, in interviews with right-wing talkers like Rush Limbaugh, Mark Levin and Sean Hannity, Rubio has drawn a series of lines in the sand, pledging to oppose any immigration bill that doesn’t reflect conservative principles. He said he wouldn’t support any legislation that doesn’t secure the border (whatever that means in practice) and set up an employment verification system (also in the eye of the beholder) before sending undocumented immigrants along a path to citizenship. He insisted that all 11 million undocumented immigrants will have to go to the “back of the line” behind foreigners who followed the rules. He demanded a special “guest worker” program for agriculture. And he said Obama’s draft proposal, by failing to address “future flow” of legal immigrants, would actually make the situation worse.

The details of these differences may matter less than the fact that there are so many of them. Rubio has left himself an awful lot of exit ramps on the long and winding highway to bipartisan legislation. Ferocious opposition from right-wing radio helped derail similar reforms during the Bush administration, and everything Rubio is saying is consistent with an effort to try to defuse that opposition. But everything Rubio is saying is also consistent with an effort to get “caught trying,” a phrase the Obama White House uses to describe losing a battle but getting credit for fighting. Rubio has already taken a stand for reform, so he’s well positioned to try to blame Obama for demanding too much if a deal doesn’t happen. He’s the only prominent Republican who could make that case en espanol. And it’s hard to think of any Republican who has suffered any political consequences for blaming Obama for anything.

“It’s not an if-Obama-is-for-it-we-have-to-be-against-it-mentality,” he told me earlier this month. “There are a lot of points of contention, and they need to be worked through to my satisfaction if I’m going to support the final product.”

So it all depends how badly Rubio really wants reform. As I wrote, it’s a personal issue for him. He comes from a family of immigrants, a community of immigrants. It’s hard to imagine a more influential lobbyist than his mom. He’d also like to transcend his reputation as an achievement-free ideologue; brokering a reform deal would show he’s capable of getting stuff done. And ever since Hispanic voters overwhelmingly rejected Mitt Romney and his “self-deportation” theories, many Republican elites have been warning that the party may be doomed in presidential elections until it can get the immigration issue off the table.

But if Rubio wants to get elected president in 2016, he’ll need to win a Republican primary dominated not by elites, but by Tea Party activists who think of the undocumented as freeloaders and the president as a nightmare. They’re a lot likelier to trust a guy who denied Obama a major victory than a guy who helped him achieve it. Rubio also has to worry about House Republicans (who generally live in fear of their own Tea Party primary challenges) derailing the reform train while he’s still on it, which would make him look ineffectual as well as Obama-appeasing. And the 2016 Republican presidential primary is starting now, while the general election won’t start until 2016; there would be plenty of time for Rubio to pivot back to reform if he won the nomination. Anyway, if Republicans decide that winning back Hispanics is their key to winning back the White House, Marco Antonio Rubio will have a leg up whether reform happens or not.

For now, if Rubio’s swipes at Obama help keep the Limbaughs and Levins of the world from launching an anti-reform crusade, they’re probably helping the cause of reform. And he’s got nothing to lose by pressing Obama to accept stricter enforcement, a more arduous path to citizenship, and other items on conservative wish lists. But eventually, there’s going to be a deal, and he’s going to have to decide whether to take it. With me, at least, he didn’t sound all that optimistic.

“I’m not trying to throw cold water on the effort,” he said. “It’s a good effort, an important effort. But we have to be realistic about the pitfalls that lie ahead. This is a very difficult problem that the country hasn’t solved in over two decades.”